There are 2 polar icecaps, Antarctica and Greenland, and if all the ice they held was melted into the ocean then the sea level would rise more than 60m, enough to cover most of Hobart. Don’t worry though. Even if that were to happen (and no serious scientist thinks it will), it would take hundreds of years for all of that ice to melt.

A much harder question to answer is how much of the polar icecaps are likely to melt, and what will happen then? Since 2006 global sea level has risen about 48 mm, about 22% from Greenland melt and 13% from Antarctica. Although Greenland is melting faster at the moment, there is much more ice in Antarctica, and in fact understanding how much Antarctic ice will melt in the future is one of the biggest questions in climate science. As well as increasing the size of the ocean, adding all that fresh (non-salty) water may change the way that the ocean
currents move water between the surface and deep ocean, which could impact sea life and the rest of the climate.

Scientists are working hard to better understand how the icecap will change in the future, both by visiting Antarctica to take measurements, and by building better computer models. In the meantime, it’s important that we take action to limit warming in Antarctica as much as possible.

What and interesting question! We asked three scientists what they'd be doing if climate change didn't exist.

This is a great question – which has several parts to it. If we stop putting large amounts of greenhouse gasses that cause climate change (like carbon dioxide and methane) into the atmosphere, it would still take several decades for warming to slow down and stop. This is because the high levels of these gases already in the atmosphere will take a long time to breakdown (in the case of methane) or be absorbed into the ocean and forests (in the case of carbon dioxide). Sea level will also continue to rise for many decades, even if we stop emitting these gases today. Stopping carbon dioxide emissions would help slow down ocean acidification, benefiting marine life and fisheries.

If climate change itself were to suddenly stop – which would be great if you had a magic wand – there are some positive things that would happen. The Earth would stop warming, and we would no longer experience the increasing temperatures and heatwaves associated with climate change. The rate of sea-level rise would also slow down. Melting glaciers and ice sheets, which are major contributors to sea-level rise, would decrease their rate of melting. The Arctic region, which has experienced significant ice loss, would start to recover. Sea ice would become more stable, which is important for the functioning of polar ecosystems. If climate change stopped completely tomorrow, many ecosystems that have been disrupted by climate change, such as coral reefs, forests, and polar environments, would have a better chance of recovering.

There would be good things that are very important to humans. Stopping climate change could improve food security by reducing crop failures and the negative impacts on agriculture caused by intense floods and droughts. Human health risks would also be reduced, as there would be less exposure to extreme heat – and many people can die during intense heatwaves.

It's important to note that while these are positive outcomes, stopping climate change would not necessarily reverse the effects that have already occurred. Many changes to ecosystems and landscapes are irreversible, and some consequences, such as the loss of certain species, may be permanent. Furthermore, global climate change is a complex process, and a sudden stop could also have unintended consequences. I hope you can think of some of these unintended consequences!

A carbon footprint is the total amount of greenhouse gases (the cause of climate change) that are generated by what we do. The carbon footprint will differ among individuals depending on their location, behaviour, and personal choices. Differences in carbon footprint between two people could come from, for example:

• The way they travel - there are no emissions when riding a bike, but a bus will have some associated emissions.
• Their location – a person using electricity in Tasmania (mostly from hydroelectric plants) will have lower emissions than someone living in Victoria (where much of the electricity is produced from coal).
• Their diet - vegetables have lower embodied emissions (emissions from production) than meat, although vegetables brought from overseas would have more emissions associated with their transport than meat produced locally.

When calculating a carbon footprint, it is important to include both direct and indirect emissions. For example, driving a non-electric car produces direct emissions from the use of fuel by the car, while using a computer produces indirect emissions from the use of electricity generated at a power station that uses fossil fuel. Similarly, a piece of paper or an apple (or anything we buy/consume) will likely have associated indirect emissions from the production and transport of the product.

Calculating your carbon footprint can be challenging but there are several online calculators that may help you to calculate emissions from various sources. Some examples are the Carbon Footprint Calculator For Individuals And Households or the ClimateHero Carbon Calculator.

It can be very frustrating to witness the slow pace of action by governments to limit climate change, particularly when we look at the record of the current Australian Federal Government. But Australia did once have a very effective climate policy. Julia Gillard's government introduced the Clean Energy Act, which put a price on carbon emissions, and operated from 2012-2013. This reduced carbon emissions by the biggest polluting companies by 7%. But the price on carbon only lasted one year because Australians voted to replace the Labor Gillard government with a Coalition government under Tony Abbott, who repealed the Act.

Since then, Australia has not had an effective national climate policy. But several state governments, local governments and and some companies have introduced their own policies. The Tasmanian Government is now legislating that Tasmania will have a Net Zero carbon emissions by 2030.

Momentum is building and we still have a small window of opportunity for our governments to make systemic change to limit global climate change to 1.5 or 2 degrees Celcius.

What are the things that make governments act on climate change?

1. Voters. If enough people of voting age tell political parties that they won't vote for them unless they promise to act on climate change, they would be forced to act, or lose power. You may not be of voting age, but you can tell the adults in your life who do vote how important this issue is to you.
2. International pressure. Australia is part of the United Nations. This organisation of 193 countries has an international convention on climate change, which Australia is a signatory to, and must abide by. The COP 26 Climate Summit in Glasgow is the latest meeting at which countries will agree on actions over the coming decade.
3. Economics. Fossil fuels are becoming risky investments, while renewable energy is a growing industry that will create more jobs and profit. Governments eventually have to face this reality, and make sure their policies enable Australians to profit from new industries, rather than propping up doomed ones.

Great question! Greta Thunberg started learning about climate change at school when she was just eight years old and her class watched documentaries about climate change. What she learnt stuck with her, and she became worried about the future and frustrated that people in power were not doing enough about it. When she was very young, she started making more sustainable choices in her life, including not eating meat or travelling by airplane.  

Greta has Asperger's syndrome, which is a condition on the autism spectrum, and she now talks about it as her superpower as a climate activist. From a very young age, she had a strong sense of what was right and wrong, and knew that if we were going to save the planet, humans have to act now.  

It was this sense of right and wrong about the environment, and her anger at world leaders ignoring the climate crisis, that led her to start protesting, starting with the Swedish government. In August 2018, when she was 15 years old, she didn't go to school and sat down outside the Swedish Parliament with a sign that read 'School Strike for Climate' and some information about climate change. She posted about her strike on social media, and slowly but surely, people came to join her in Sweden, and then around the world.  

Greta now is a fierce climate activist and continues to fight for climate action and climate justice. One of the best things about her story is that she did not start out trying to become famous or start a worldwide movement, but instead she chose something that she could do in her own life. Just by taking a small action, she inspired other people to take action too. Anybody can be a Greta, just start small and stick with it! 

Hmm, that’s an interesting (and slightly scary) question. The only reason that Earth may ‘explode’ is if a meteorite the size of the moon impacted the Earth. Large meteorites have impacted Earth before, for example 66 million years ago and that meteorite was probably at least 10-80 km in diameter. That impact caused the outpouring of huge volumes of hot liquid magma in lots of places on Earth’s surface and changed Earth’s climate. The dinosaurs and many reptiles couldn’t cope with those changes and became extinct, which then enabled the mammals to flourish.

Here in Tasmania we also have craters associated with the impact of Meteorites – for example Darwin Crater in southwest Tasmania. That impact was probably around 820,000 years ago.

Interestingly, scientists are now using sediment cores taken from the Darwin crater to find out how the climate changed more than 20,000 years ago.